L. Van Landuyt

Chromosomal aneuploidy in embryos conceived with unstimulated cycle IVF

There is an ever increasing trend in reproductive medicine to reduce the intensity of ovarian stimulation for in vitro fertilization (IVF) and to restrict the number of embryos that are transferred into the uterine cavity. Recent findings suggest that the magnitude of ovarian stimulation affects the proportion of euploid embryos. As a result of the restriction in the number of embryos transferred, it becomes even more important to select the embryo with optimum implantational and developmental potential. Our aim was to asses the prevalence of numerical chromosomal abnormalities (aneuploidy) in unstimulated cycle IVF embryos. Thirty patients (mean age 31.4 years) underwent oocyte retrieval in a natural cycle without any form of ovarian stimulation, followed by intracytoplasmic sperm injection and Preimplantation genetic aneuploidy screening (PGS) for chromosomes X, Y, 13, 16, 18, 21 and 22. Out of 30 cycles, 21 oocytes were retrieved, 15 of which fertilized successfully. Eleven embryos developed sufficiently in order to undergo the PGS analysis, and four embryos proved to be aneuploid (36.4%; 95% CI: 10.9-69.2%). Six normal embryos were transferred in utero, resulting in three ongoing pregnancies. Two healthy girls were born and one patient miscarried. Numerical chromosomal abnormalities (aneuploidy) are present even in embryos of young women, and in the absence of ovarian stimulation.

Influence of cell loss after vitrification or slow-freezing on further in vitro development and implantation of human Day 3 embryos

STUDY QUESTION Is the effect of cell loss on further cleavage and implantation different for vitrified than for slowly frozen Day 3 embryos? SUMMARY ANSWER Vitrified embryos develop better overnight than slowly frozen embryos, regardless of the number of cells lost, but have similar implantation potential if further cleavage occurs overnight. WHAT IS KNOWN ALREADY After slow-freezing, similar implantation rates have been obtained for intact 4-cell embryos or 4-cell embryos with 1 cell damaged. For slowly frozen Day 3 embryos, lower implantation rates have been observed when at least 25% of cells were lost. Other studies reported similar implantation potential for 7- to 8-cell embryos with 0, 1 or 2 cells damaged. No data are available on further development of vitrified embryos in relation to cell damage. STUDY DESIGN, SIZE, DURATION Survival and overnight cleavage were retrospectively assessed for 7664 slowly frozen Day 3 embryos (study period: January 2004-December 2008) and 1827 vitrified embryos (study period: April 2010-September 2011). Overnight cleavage was assessed according to cell stage at cryopreservation and post-thaw cell loss for both protocols. The relationship between cell loss and implantation rate was analysed in a subgroup of single-embryo transfers (SETs) with 780 slowly frozen and 294 vitrified embryos. PARTICIPANTS/MATERIALS, SETTING, METHODS Embryos with ≥6 blastomeres and ≤20% fragmentation were cryopreserved using slow controlled freezing [with dimethyl sulphoxide (DMSO) as cryoprotectant] or closed vitrification [with DMSO-ethylene glycol (EG)-sucrose (S) as cryoprotectants]. Only embryos with ≥50% of cells intact after thawing were cultured overnight and were only transferred if further cleaved. For each outcome, logistic regression analysis was performed. MAIN RESULTS AND ROLE OF CHANCE Survival was 94 and 64% after vitrification and slow-freezing respectively. Logistic regression analysis showed that overnight cleavage of surviving embryos was higher after vitrification than after slow-freezing (P < 0.001) and decreased according to the degree of cell damage (P < 0.001). If the embryo continued to cleave after thawing, there was no effect of the number of cells lost or the cryopreservation method on its implantation potential. The implantation rates of embryos with 0, 1 or 2 cells damaged were, respectively, 21% (n = 114), 21% (n = 28) and 20% (n = 12) after slow-freezing and 20% (n = 50), 21% (n = 5) and 27% (n = 4) after vitrification. LIMITATIONS, REASONS FOR CAUTION This analysis is retrospective and study periods for vitrification and slow-freezing are different. The number of SETs with vitrified embryos is limited. However, a large number of vitrified embryos were available to analyse the further cleavage of surviving embryos. WIDER IMPLICATIONS OF THE FINDINGS Although it is not proved that vitrified embryos are more viable than slowly frozen embryos in terms of pregnancy outcome, vitrification yields higher survival rates, better overnight development and higher transfer rates per embryo warmed. This increases the number of frozen transfer cycles originating from a single treatment and might result in a better cumulative clinical outcome. Based on the present data, the policy to warm an extra embryo before overnight culture depends on the cell stage at cryopreservation and the cell damage after warming. For 8-cell embryos, up to two cells may be damaged compared with only one cell for 6- to 7-cell embryos, before an additional embryo is warmed. STUDY FUNDING/COMPETING INTEREST(S) none.

Closed blastocyst vitrification of biopsied embryos: evaluation of 100 consecutive warming cycles

BACKGROUND The aim of this study was to analyse the outcome of closed blastocyst vitrification of embryos biopsied at the cleavage stage. METHODS Vitrification of supernumerary blastocysts was performed using the closed CBS-VIT High Security straws. Warming cycles (n = 100) for patients with preimplantation genetic diagnosis (PGD) and/or aneuploidy screening in the fresh cycle were analysed. The outcome parameters were morphological survival and transfer rates after warming, clinical pregnancy rate and implantation rate (with fetal heart beat). Clinical outcome was compared with two control groups of (i) vitrified/warming transfer cycles without embryo biopsy and (ii) fresh Day 5 transfer of biopsied embryos. RESULTS In total, 131 blastocysts were warmed with a morphological survival of 83.2% (109/131) and a transfer rate of 79.4% (104/131). Day 5 blastocysts survived significantly better (90.4%) than Day 6 blastocysts (70.8%, P < 0.01). No difference in survival rate was observed between early cavitating (89.2%) and full/expanded blastocysts (93.3%). In nine cycles, no blastocyst was available for transfer. The clinical pregnancy rate was 19.2% (15/78) after single-embryo transfer (SET) and 38.5% (5/13) after double-embryo transfer (DET). In SET, the implantation rate for blastocysts frozen on Day 5 was 13.7% (7/51), which was not different from the implantation rate of Day 6 blastocysts (18.5%, 5/27). The overall implantation rate of vitrified PGD biopsied blastocysts (14.4%) was comparable with that of vitrified blastocysts without biopsy (20.4%), but lower than the implantation rate obtained in the fresh PGD cycles (24.4%). CONCLUSION Blastocysts on Day 5 and Day 6 of development derived from biopsied embryos can be successfully vitrified using a closed system.

Neonatal health including congenital malformation risk of 1072 children born after vitrified embryo transfer

STUDY QUESTION Does vitrification of Day 3 and Day 5 embryos adversely affect birth outcomes of singletons and twins in comparison with peers born after fresh embryo transfer? SUMMARY ANSWER Neonatal health parameters, including the prevalence of congenital malformations, in singletons and twins born after embryo vitrification are similar to or slightly better than after fresh embryo transfer. WHAT IS ALREADY KNOWN Although vitrification, rather than slow-freezing, of embryos is routine practice nowadays, convincing evidence regarding the safety for the offspring is sparse. Literature data comprise results from mostly small-sized studies or studies including only Day 3 or only Day 5 vitrified embryo transfers. Overall, better or comparable perinatal outcomes, in terms of higher birthweight and lower risk for small-for-gestational age or for low birthweight, have been reported for singletons born after vitrified embryo transfer compared with fresh embryo transfer. According to the single available study with sufficient sample size, the congenital malformation rate was found to be comparable after vitrified and fresh embryo transfers. STUDY DESIGN, SIZE, DURATION Data were collected from 960 cycles after transfer of embryos vitrified on Day 3 (n = 457) or Day 5 (n = 503) and from 1644 cycles after fresh embryo transfer on Day 3 (n = 853) or Day 5 (n = 791), performed between 2008 and 2013 at the Centre for Reproductive Medicine of the university hospital UZ Brussel. Outcome measures were neonatal health in terms of birthweight, small-for-gestational age, prematurity rate, perinatal death and major/minor/total malformation rate. PARTICIPANTS/MATERIALS, SETTING, METHODS Perinatal health parameters of 11 stillborns and 1061 live borns (827 singletons and 234 twins) in the vitrified group and of 28 stillborns and 1838 live borns (1374 singletons and 464 twins) in the fresh embryo group are reported. Within 3 months after birth, children in the two study groups were assessed clinically with special attention to congenital malformations by a paediatrician blinded to the type of embryo transfer. Data were analysed by multiple linear and logistic regression, adjusted for treatment variables and maternal characteristics. MAIN RESULTS AND THE ROLE OF CHANCE Mothers to infants in the vitrified group were on average slightly older and more often suffering from pregnancy-related hypertensive disorders than mothers to infants in the fresh transfer group. Singletons born after vitrification showed a higher birthweight standard deviation score (SDS) (-0.4 versus -0.7; 95% confidence interval (CI): 0.0-0.3, P = 0.001) and a lower small-for-gestational age rate (AOR: 0.55; 95% CI: 0.34-0.90) in comparison with peers born after fresh embryo transfer. Preterm birth rate and perinatal death rate were comparable between the two groups (AOR: 0.91; 95% CI: 0.57-1.43 and AOR: 0.97; 95% CI: 0.40-2.36). In twins, neonatal outcomes including birthweight SDS, small-for-gestational age and prematurity rates were comparable in the vitrified and the fresh groups, when adjusted for confounders. Furthermore, the rate of major congenital malformations in live borns was comparable between the vitrified group and the fresh group, both in singletons (2.6 versus 2.8%; AOR: 0.91; 95% CI: 0.47-1.78) and in twins (2.4 versus 2.7%; AOR: 0.51; 95% CI: 0.05-5.72). Also, the total malformation rate in the vitrified group (3.4%; 95% CI: 2.4-4.8) did not differ from the rate in the fresh embryo group (3.9%; 95% CI: 3.1-5.0). The embryonic stage at vitrification or fresh transfer (cleavage-stage embryo or blastocyst) did not influence the birth characteristics or malformation rate. LIMITATIONS, REASONS FOR CAUTION The main limitation of this study is the rather small twin group. Therefore, the outcome results for twins should be interpreted cautiously. WIDER IMPLICATIONS OF THE FINDINGS This study provides evidence that transfer of vitrified Day 3 and Day 5 embryos does not adversely affect the neonatal health of the offspring in comparison with transfer of fresh embryos. Furthermore, neonatal outcomes were not different after transfer of vitrified blastocysts compared with transfer of vitrified cleavage-stage embryos. STUDY FUNDING/COMPETING INTERESTS Educational grants for establishing and organizing the data collection have come from IBSA, Ferring, Organon, Shering-Plough and Merck. Merck Belgium funded the data collection for outcomes after vitrification between 2012 and 2015. All co-authors, except M.B., declared no conflict of interest. M.B. has received consultancy fees from Organon, Serono Symposia and Merck.

Cryopreserved embryo transfer in an artificial cycle: is GnRH agonist down-regulation necessary?

The use of GnRH agonist downregulation in artificial endometrium priming cycles for cryopreserved embryo transfer was retrospectively investigated to establish whether higher live birth rates resulted. Six hundred and ninety-nine patients underwent 1129 artificial endometrium priming cycles for the transfer of cryopreserved embryos between 1 July 2009 and 1 June 2012. Hormonal supplementation with (group A, n = 280 cycles) or without (group B, n = 849 cycles) GnRH agonist co-treatment was given. Live birth rates were comparable between the two groups per started cycle (14.9% [41/275] in group A versus 15.1% [127/839] in group B) or per embryo transfer (17.5% [41/234] in group A versus 17.6% [127/723] in group B). After logistic regression analysis, the only variables that were significantly associated with live birth rates were day of embryo transfer (OR 0.69; 95% CI 0.48 to 0.98) for day 3 versus day 5 embryos, the number of embryos transferred (OR 2.13; 95% CI 1.58 to 2.86) for two embryos versus one embryo transferred and the endometrial thickness on the day of embryo transfer (OR 1.15; 95% CI 1.05 to 1.25). Live birth rates after cryopreserved embryo transfer in artificial cycles did not increase when a GnRH agonist was administered.

A prospective randomized controlled trial investigating the effect of artificial shrinkage (collapse) on the implantation potential of vitrified blastocysts

STUDY QUESTION What is the effect of artificial shrinkage by laser-induced collapse before vitrification on the implantation potential after transfer of vitrified-warmed blastocysts? SUMMARY ANSWER The artificial shrinkage by laser-induced collapse did not significantly increase the implantation rate per transferred collapsed blastocyst (37.6%) compared with non-collapsed blastocysts (28.9%) [odds ratio (OR): 1.48, 95% confidence interval (CI): 0.78-2.83]. WHAT IS KNOWN ALREADY Retrospective studies have demonstrated that artificial shrinkage of the blastocyst prior to vitrification can have a positive effect on blastocyst survival after warming. A recent study found a similar survival rate but higher implantation rate for collapsed blastocysts. So far, no randomized controlled trial has been conducted to investigate the implantation potential of collapsed blastocysts. STUDY DESIGN, SIZE, DURATION Prospective randomized trial. Patients were recruited from December 2011 until April 2014 and warming cycles were included until July 2014. Patients were randomized in the fresh cycle if blastocysts were available for vitrification and were allocated to the study or control arm according to a computer-generated list. In the study group, blastocysts underwent laser-induced collapse before vitrification. In the control group, blastocysts were vitrified without collapsing. PARTICIPANTS/MATERIALS, SETTING, METHODS In total, 443 patients signed informed consent and 270 patients had blastocysts vitrified. One-hundred and thirty-five patients were allocated to the study group and 135 to the control group. Sixty-nine patients from the study group and 69 from the control group returned for at least one warming cycle in which 85 and 93 blastocysts were warmed in the first cycle, respectively. Primary outcome was implantation rate per embryo transferred in the first warming cycle. Secondary outcomes were survival and transfer rates, blastocyst quality after warming, clinical pregnancy rate and implantation rate per warmed blastocyst. Blastocysts were vitrified-warmed one by one using closed vitrification and one or two blastocysts were transferred per warming cycle. MAIN RESULTS AND THE ROLE OF CHANCE We calculated that the group sample sizes of 80 embryos in the collapse group and 80 embryos in the control group were needed to achieve 80% power to detect a difference between the group proportions of +20% with P < 0.05. In the study group, 69 first warming cycles resulted in 69 transfers with 1.2 blastocysts (n = 85) transferred. In the control group, an average of 1.3 blastocysts (n = 83) were transferred in 67 out of 69 warming cycles. Implantation rates per embryo transferred in the first warming cycle were not different between both groups (38 versus 29%, OR: 1.48; 95% CI: 0.78-2.83), neither was the implantation rate per warmed embryo (38 versus 26%, OR: 1.74; 95% CI: 0.92-3.29). When all warming cycles were considered (n = 135 in each group), survival rate after collapse was significantly higher compared with the control group (98.0 versus 92.0%, OR: 4.25; 95% CI: 1.19-15.21). Furthermore, a higher percentage of high-quality blastocysts (36.3 versus 23.5%, OR: 1.86; 95% CI: 1.12-3.08) and hatching blastocysts (19.2 versus 5.4%, OR: 4.18; 95% CI: 1.84-9.52) were found compared with the control group. LIMITATIONS, REASONS FOR CAUTION The study lasted more than 2.5 years since fewer patients than expected returned for a warming cycle because of the high ongoing pregnancy rates in the fresh IVF/ICSI cycle. WIDER IMPLICATIONS OF THE FINDINGS Although no significant higher implantation rate was found after collapse, the better survival and post-warm embryo quality convinced us to recognize a clinical benefit of artificial shrinkage and to implement it in routine vitrification practice. TRIAL REGISTRATION NUMBER NCT01980225, www.clinicaltrials.gov. The first patient was included November 2011 and the study was registered October 2013.

Randomized sibling-oocyte study using recombinant human hyaluronidase versus bovine-derived Sigma hyaluronidase in ICSI patients

BACKGROUND The enzyme hyaluronidase from bovine origin is commonly used for oocyte-cumulus cell removal in ICSI. A recombinant human hyaluronidase (rHuPH20) has been introduced as a quality-controlled and safe alternative. METHODS In order to validate its effectiveness, a non-inferiority trial was started on sibling cumulus-oocyte complexes (135 ICSI patients). Oocyte denudation involved enzyme incubation under Pasteur pipetting, followed by further mechanical stripping. Primary end-points were oocyte intactness after ICSI and fertilization rate. Secondary end-points were embryo development and positive hCG. RESULTS Oocyte intactness after ICSI was 89.6% and 92.9% with rHuPH20 and bovine hyaluronidase, respectively [absolute difference -3.3% (-7.4 to 10.7)]. The fertilization rate was 73.9% after rHuPH20 and 77.1% after bovine hyaluronidase treatment [absolute difference -3.2% (-8.3 to 1.8)]. Embryo development was similar in both treatment groups up till Day 5. Positive hCGs were equally distributed over mixed transfers 21/45 (46.7%) and transfers of only embryos from rHuPH20 treatment 17/35 (48.6%) or transfers of only embryos from bovine hyaluronidase treatment 22/48 (45.8%). CONCLUSIONS Our results indicate that rHuPH20 is not inferior to bovine hyaluronidase for oocyte denudation, with regard to oocyte survival and fertilization. rHuPH20 treatment of human oocytes is compatible with good embryo development, with positive hCG results and with live birth.

Offering excess oocyte aspiration and vitrification to patients undergoing stimulated artificial insemination cycles can reduce the multiple pregnancy risk and accumulate oocytes for later use

BACKGROUND The prevention of multiple pregnancies remains a major challenge in patients treated with ovarian stimulation prior to intrauterine insemination (IUI). The pilot study presented here investigates whether multiple pregnancies can be minimized by a microscopically confirmed aspiration of oocytes from supernumerary follicles immediately before intrauterine insemination and evaluates the benefit of concomitant excess oocyte cryopreservation for future use. METHODS Thirty-four aspirations of supernumerary follicles were performed immediately prior to IUI in 31 patients undergoing ovarian stimulation. sIUI was only performed if cumulus-oocyte complexes were microscopically observed in the aspirated follicular fluid. All collected mature excess oocytes were cryopreserved using the vitrification technique. RESULTS Only four sIUI procedures had to be cancelled due to failed oocyte retrieval or premature ovulation. IUI treatment resulted in a clinical pregnancy rate of 23.5% per cycle. All were singleton pregnancies. A total of 111 oocytes were cryopreserved. Patients with polycystic ovary syndrome (PCOS) had an average of 6.07 oocytes vitrified, whereas patients without PCOS had 1.3 oocytes vitrified per cycle. CONCLUSION Microscopically confirmed collection of excess oocytes prior to stimulated IUI reduced cancellation rates, further reduced the risk for multiple pregnancy and may lead to future additional pregnancies because, based on current information, approximately 5% of the vitrified oocytes could potentially establish a pregnancy.

Vitrified-warmed blastocyst transfer on the 5th or 7th day of progesterone supplementation in an artificial cycle: a randomised controlled trial

Abstract Prospective studies comparing different durations of progesterone supplementation before transfer of vitrified-warmed blastocysts in an artificial cycle are lacking. However, in oocyte donation programmes, the sporadic available evidence demonstrates considerable differences in clinical pregnancy rates according to the duration of progesterone administration. This randomised controlled trial (RCT), included 303 patients undergoing a frozen-thawed embryo transfer (FET) of one or two vitrified-warmed blastocyst(s) in an artificial cycle. Randomisation was performed when the endometrial thickness reached ≥7 mm after oestrogen supplementation. One hundred and fifty two patients in group A received 7 d of vaginal micronised progesterone tablets and 151 patients in group B received 5 d of micronised vaginal progesterone before FET. No differences were seen in clinical pregnancy rate between both groups: 42/152 (27.6%) in group A versus 49/151 (32.5%) in group B. Although no statistically significant difference was observed in clinical pregnancy rates, our study was powered to detect an absolute difference of 16%. In this regard, we cannot exclude that smaller, clinically relevant differences might exist and our study did not have the power to detect this. Patients were also not blinded for the intervention, causing a potential bias.